The impact of lymph node dissection and positive lymph nodes on cancer-specific mortality in contemporary pT2-3 non-metastatic renal cell carcinoma treated with radical nephrectomy

OBJECTIVE: To assess the effect of lymph node dissection (LND), number of removed nodes (NRN), and number of positive nodes (NPN), on cancer-specific mortality (CSM) in contemporary vs historical patients with pT2-3 Nany M0 renal cell carcinoma (RCC) treated with radical nephrectomy (RN). PATIENTS AND METHODS: Within the Surveillance, Epidemiology, and End Results database (2001-2013), we identified patients with non-metastatic pT2-3 Nany RCC who underwent RN with or without LND. Kaplan-Meier analyses and multivariable Cox regression models with propensity score weighting for inverse probability of treatment were used. RESULTS: Of 25 357 patients, 24.8% underwent LND (2001-2007: 3 167 patients vs 2008-2013: 3 133 patients). The median NRN was 3 (interquartile range [IQR]: 1-7). Positive nodes were identified in 17.1%: 9.3% of pT2 and 21.6% of pT3 patients, who underwent LND. The median NPN was 2 (IQR: 1-3). In multivariable models, LND did not decrease CSM (hazard ratio [HR] 1.29; P < 0.001). LND extent, defined as NRN, did not decrease CSM (HR 0.94; P = 0.3). Finally, multivariable models testing the effect of NPN showed increased CSM in pT3 but not in pT2 patients (HR 1.29 and 1.58, P = 0.02 and P = 0.1, respectively). NRN exerted a protective effect on CSM in patients with positive nodes (HR 0.98; P = 0.007).